What is the Floridan aquifer? 

The Floridan aquifer is an underground system of caves and porous rock that stretches across 100,000 square miles and produces 1.2 trillion gallons of water every year.  

Florida rests on a bedrock made of limestone that formed when the state still lay under a shallow, warm sea. This sedimentary rock was made by the compression of calcareous (made of calcium) matter, like marine shells, corals, and skeletons, over the course of millions of years. Once the ancient sea receded from the peninsula that is now Florida, a thick limestone layer was revealed.  

Over time, naturally acidic rainwater has slowly dissolved this limestone layer, peppering it with holes, tunnels, and caverns. This kind of geology is called “karst,” and is marked by formations that you can see across Florida, including sinkholes and caves.  

 

The ancient sea, limestone layer, and resulting karst topography, have paved the way for the Floridan aquifer, which holds and circulates water throughout the state. Some of this water has been dated to 26,000 years old, a relic of a time before people even arrived on the land that is now Florida.  

How is the aquifer recharged? 

The aquifer is continuously “recharged,” or replenished, with rainwater that slowly filters through the ground. It supplies drinking water for about 90% of Florida’s population, making it an invaluable, and irreplaceable, resource. It also feeds over a thousand springs across the state, which are iconic Floridian landscapes supporting wildlife, recreation, and more.  

What’s going on? 

The Floridan aquifer continues to face many threats today, including:  

1. Overexploitation:  

Aquifer resources are actively being overexploited for agriculture, personal irrigation, industry, and more. Half of all public supply water drawn from the aquifer goes directly to irrigate private lawns. As a result, springs around the state have diminished in volume and strength, and drinking water availability may be affected in the future. Silver Springs, which was once the strongest flowing spring in the state, has slowed by over 30% in the last century, largely due to aquifer over extraction.  

 2. Contamination

Florida’s growing population and expanding development have also led to statewide losses of natural drainage areas, like wetlands, and an increase in impermeable surfaces, like parking lots. Paved areas increase stormwater runoff, allowing it to collect contaminants and dump them into the environment. Too much runoff can also prevent rainwater from replenishing the aquifer by directing it into other water bodies.  

 3. Saltwater Intrusion: 

 As more freshwater is extracted, there is room for underlying saltwater to rise and infiltrate, or “intrude” into the aquifer. This saltwater intrusion is worsened when sea levels rise and exert more pressure on the aquifer from below. Increased salinity in our water sources negatively impacts soil heath and agricultural practices, 

 What can you do? 

To help protect the Floridan aquifer and encourage aquifer recharge, you can:  

• Reduce or eliminate fertilizers and pesticides in your yard to prevent contaminants from entering the environment. 

• Build a rain garden in your yard to decrease stormwater runoff and encourage natural drainage and filtration of rainwater.  

• Reduce or eliminate irrigation in your yard to save water! 

 

Information from UF IFAS, North Florida Land Trust, St. John’s River Water Management District, USGS, Argonne National Laboratory, Florida Department of Environmental Protection, Suwannee River Water Management District, Florida Department of State, and Blue Water Audit. 

 Images from Canva Pro.